MSD Secrets to Successfully Using an MSD Magnetic and Non-Magnetic Pickup Tech Bulletin - Manual

Secrets to Successfully Using
an MSD Magnetic and
Non-Magnetic Pickup
MSD’s Tech Bulletins are designed to give you a more in-depth
understanding of the ignition system and its components. If you have any other questions about the
subject or MSD products you can contact our Customer Support Department at (915) 855-7123 or
email your questions to [email protected].
# 109
Every ignition system requires a trigger signal to accurately fire and deliver a high voltage spark from the coil. There
are several ways this is achieved, from mechanical breaker points to magnetic pickups, optical triggers and other elec-
tronic switches which all serve the same function; to accurately trigger the ignition at the correct moment for the ideal
spark timing.
MSD Ignition incorporates a magnetic pickup in our distributors because of their reliability and accuracy. In fact, most
major automotive manufacturers used magnetic pickups in their distributors until the advent of distributorless ignition
systems in late model vehicles. (For MSD’s Flying Magnet Crank Trigger systems, a non-magnetic pickup is used. This
pickup functions in a similar manner as the magnetic pickup which will be explained below.)
This bulletin provides an explanation as to the operation of a magnetic pickup and non-magnetic pickup, their polarity
and testing along with a few helpful installation tips.
Secrets to Successfully Using
an MSD Magnetic and
Non-Magnetic Pickup
Figure 2 - MSD Flying Magnet Crank Trigger.
Theory – How Does It Work?
The magnetic pickup is actually a wire that is wound around
a magnet to create a magnetic field. Whenever this field
changes, due to another metal object coming into the field,
a voltage is generated. MSD uses this voltage as a trigger
signal for the ignition control.
An MSD Distributor incorporates a metal reluctor wheel
with eight evenly spaced trigger tabs (six for 6-cylinder en-
gines, four on 4-cylinders). This reluctor is mounted to the
distributor shaft (Figure1). Each time one of these reluctor
tabs passes the magnetic pickup, a trigger signal is created
which fires the MSD Ignition.
Conversely, an MSD Flying Magnet Crank Trigger system
uses a non-magnetic pickup. The pickup consists of a wire
that is wound around an iron core rather than a magnet. To
create the voltage for the trigger signal, a magnet must pass
the pickup rather than a metal post (Figure 2). MSD uses this
design because we have the capability to install magnets in
a crankshaft mounted wheel and the pickup cannot be trig-
gered by anything other than the magnet so there are no
chances of false triggering.
Though these two pickups require different trigger sources,
they essentially function in the same manner and share the
same wiring and installation tips.
Figure 1 - MSD Pro-Billet Distributor.
RELUCTOR
TRIGGER TABS
MAGNETIC
PICKUP
TRIGGER
MAGNET
NON-MAGNETIC
PICKUP
®
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frm28388_ tech_bulletin_109.indd1 1 2/22/2007 11:42:19 AM